# Select Every Nth

Keeps every nth frame of an `IMAGE` batch — halve a video's frame count
before an expensive stage, or thin a long sweep down to samples.

## Controls

- **images**: The BHWC batch to thin out.
- **Every nth** (`nth`): Keep one frame in every `nth`. `2` keeps every
  other frame, `1` keeps everything (useful with **offset** alone to drop
  leading frames).
- **offset**: Frames to skip before the first kept frame. With `nth` 2,
  offset `0` keeps frames 1, 3, 5 and offset `1` keeps frames 2, 4, 6
  (one-based, as the rest of the pack counts frames).
- **fps** (optional socket): The batch's frame rate, such as Load Video's
  `fps` output.

## Outputs

- **images**: The kept frames, in their original order.
- **fps**: The wired rate divided by `nth`, so the kept frames still span
  the same time; `0` when no fps is wired.

An offset at or past the end of the batch stops with the batch's size
instead of returning an empty batch, which no downstream node could use.